High school students using e-cigarettes will likely graduate to tobacco, a two-year University of Hawaii Cancer Center study found after following 2,300 Hawaii teenagers.

E-cigarette use, or “vaping,” among high-schoolers has exploded in the last four years, up to 20 to 30 percent now from 1 to 2 percent, UH Cancer Center’s Prevention and Control Program Interim Director Thomas Wills said.

The study by Wills and other collaborators, published Monday in the journal Tobacco Control, was based on data collected starting in 2012 from 2,300 Hawaii high-schoolers, mostly ninth- and 10th-graders.

“For several years people have asked if e-cigarettes make young people more inclined to smoke … or if it does the opposite and helps teens who are smoking to quit,” Wills said, adding there had been no scientific evidence on the matter until recently.

Another study, conducted by Dr. Neal Benowitz, professor of medicine at the University of California, San Francisco, shows nicotine use in adolescents can hinder brain development, which can lead to increased risk-taking, impulsiveness, novelty-seeking, vulnerability to using and subsequent addiction to drugs.

Wills said, “We’re able to provide high-quality data, making a big impact on possible federal regulations.” The findings of the UH Cancer Center study, which includes a large sample and high rate of participation, are being folded into a scientific database used by the Food and Drug Administration as the agency considers e-cigarette and tobacco regulations.

As of Jan. 1, Hawaii banned the sale of tobacco and electronic smoking devices to anyone under age 21. Previously, such purchases could be made by anyone age 18 or older.

“We would like to see all advertising toned down or eliminated” for e-cigarettes, Wills said. “If you look around Honolulu, you see advertising everywhere, including prime-time TV.”

Wills said the Cancer Center study focused on behavior rather than physiological reasons that point to e-cigarettes as a gateway to tobacco use.

The study found that students of Native Hawaiian and Filipino backgrounds had a higher use of e-cigarettes compared with other ethnic backgrounds, including Japanese, Chinese and Korean.

Youth, regardless of ethnicity, with perceived higher levels of emotional support and understanding from parents were less likely to start using e-cigarettes, the study showed.

It also found that students from families with lower education in all ethnic groups were more likely to use both types of cigarettes, Wills said.

“We have suspicions and suggestions” as to why some groups might smoke or use e-cigs more, Wills said. “Laboratory studies show stress increases smoking rates in animals and humans. … The more stress, then the more likely you are to smoke.”

Department of Health Tobacco Prevention and Education Program Manager Lila Johnson said, “The findings … confirm the importance of protecting our youth from initiating e-cigarette use.”

The study was part of an existing $200,000 federally funded survey.

Wills said tropical flavors such as pineapple and mango in the flavored liquid used in e-cigarettes might entice local teens. The cost may also be another factor.

“In Hawaii it’s cheaper to use e-cigarettes,” he said. “Cigarettes are heavily taxed. That may be part of the reason why e-cigarette use is particularly high in Hawaii.”

As for use as a smoking cessation tool, Wills said, “If you’re a smoker and you’re using e-cigarettes, you’re less likely to quit compared to smokers who just use cigarettes.”

The harm of nicotine alone has been debated, but there’s no question that it is addictive, he said, adding that some lab results show a greater likelihood of becoming nicotine-dependent over heroin-dependent.

While cigarette combustion byproducts and tars are cancer-causing agents in tobacco-burning cigarettes, researchers are still pinpointing the extent of damage nicotine causes.

There is solid evidence that nicotine is a tumor promoter. “If you have a tumor, nicotine will accelerate the growth,” Wills said.

The UH study did not address other ingredients in the liquids used to create the vapor in e-cigarettes. But preliminary research shows they contain toxic compounds, such as formaldehyde and acetone, as well as heavy metals, which are also linked to cancer and possibly to asthma and emphysema, said Rebecca Williams, assistant professor at the UH Cancer Center.

The harm comes from both inhaling the vapor and secondhand exposure, Williams said.

“If they’re not regulated by the FDA, the companies can put into them whatever they want,” she said, adding that various types of e-cigarettes are being purchased from China, the United States and elsewhere.

Studies are ongoing to understand the long-term consequences of the e-cigarette vapor, Williams said.

The physiological effects of nicotine overdose include headaches, dizziness, vomiting, coma, abdominal cramps, agitation, restlessness, excitement, confusion, convulsions, depression, difficulty breathing, stopped breathing, fainting, irregular heartbeat, muscle twitching and weakness.